Electronic components of the above-specified kind are usually identified by the abbreviation MIS (metal insulator semiconductor) or, in their most common and most significant configuration, MOS (metal oxide semiconductor). There are known for example MOS diodes, MOS field effect transistors (MOSFET), scaled MOSFETs in which material parameters such as doping are adapted to reduce lateral dimensions of the component structure, modulation-doped MODFETs or DRAM structures.
It should be noted that the metallically conductive first layer of such components can be formed both by metals themselves and also by highly doped (degenerate) semiconductors. In both groups of materials charge transport is effected in the first layer in the electrical field by means of virtually free charge carriers.
It should further be emphasised that the term ‘layer’ used herein does not necessarily imply a surface extent which is large in comparison with the layer thickness, in (lateral) directions, perpendicularly to the sequence of layers. Subsequent structuring or suitable adjustment of the production parameters, for example in epitaxial production processes, make it possible to produce in electronic components structures whose lateral dimensions are of the order of magnitude of the layer thickness. Such structures are also referred to herein as a ‘layer’.
The use of silicon oxide SiO2 as a dielectric in the third layer of electronic components of the kind set forth in the opening part of this specification has encountered physical limits in the recent past. Thus the reduction in the structural dimensions in the case of CMOS (complementary MOS) field effect transistors requires a reduction in the thickness of the gate dielectric between the metallically conductive gate electrode and the doped semiconductor channel. For transistors with channel lengths between the source and the drain of less than 100 nm, when using SiO2 as the gate electrode, by virtue of the relatively low dielectric constant of 3.9, a dielectric layer thickness of less than 2 nm is required. That small layer thickness increases the probability of direct tunnelling of charge carriers and therefore causes markedly increased leakage currents between the gate electrode and the channel or drain, which can adversely affect the efficiency of the transistor.
To resolve the problem, it is known to use alternative materials which can replace silicon oxide as the dielectric. Materials of that kind have a higher dielectric constant than silicon oxide. Thus, having regard to scaling of the component, it is possible to achieve an increase in the gate-oxide capacitance without reducing the layer thickness to a critical range of values in which there is a great probability of direct tunnel processes. As is known the gate-oxide capacitance is proportional to the dielectric constant and anti-proportional to the thickness of the gate dielectric.
Known alternative dielectrics are metal oxides in a predominantly amorphous phase. U.S. Pat. No. 6,013,553, to Wallace, discloses the use of zirconium or hafnium oxynitride as the gate dielectric. U.S. Pat. No. 5,955,213 discloses the use of crystalline YScMnO3 as a gate dielectrode in memory components. U.S. Pat. Nos. 5,810,923 and 5,828,080 disclose the use of an epitaxial ZrO2 layer or ZrYO2 layer as the gate dielectric. Those materials admittedly permit a reduction in the leakage current density in comparison with an SiO2 layer. Here the value of the leakage current density, with the same equivalent oxide layer thickness EOT serves as a comparative measurement. The equivalent oxide layer thickness EOT (Equivalent Oxide Thickness) of a dielectric is the product of the layer thickness d and the ratio of the dielectric constants of silicon oxide (KSiO2) and the dielectric (KD):
                    EOT        =                  d          ·                                    K              SiO2                                      K              D                                                          (        1        )            
The values of the leakage current density of ZrO2 and HfO2 with a given value of EOT=1.4 nanometers, which are known from the publications by B H Lee et al, Techn. Dig IEEE International Electron Devices Meeting 1999 (IEDM '99), pages 133 and W J Qi et al, Techn. Dig IEDM '99, pages 145, are admittedly reduced in relation to known values of SiO2 with a gate voltage of 1 V by a factor of up to about 10−4 to values of between about 10−3 and 10−4 A/cm2. However a further reduction in the leakage current density is desirable in order to be able to produce components involving a particularly high degree of scaling, that is to say particularly low dimensions in respect of the relevant component structures.
P Singh, B Baishya, phys stat sol (a) 104, 1987, 885–889 report about investigations into various rare earth oxides, including also predominantly amorphous praseodymium oxide Pr6O11 in terms of the suitability thereof for use as a gate dielectric in thin-film transistors consisting of II–VI semiconductors. The production of such thin-film transistors was effected by means of a ‘multiple-pump-down’ process by the vaporisation of solid starting materials under the action of an electron beam in a vacuum chamber. The components produced in that way were then subjected to a step of thermal curing in ambient air at 200° C. over between 3 and 4 hours. The components produced in that way, with a praseodymium oxide layer, are of low strength.
The object of the invention is to develop an electronic component of the kind set forth in the opening part of this specification, in such a way that it can be particularly highly scaled. Another object of the invention is to develop a process for the production of an electronic component, including a step of depositing a praseodymium oxide-bearing material layer from a gaseous atmosphere on a substrate, in such a way that particularly highly scaled components can be produced.